diff --git a/src/pkg/runtime/alg.go b/src/pkg/runtime/alg.go new file mode 100644 index 00000000000..9d06197f27d --- /dev/null +++ b/src/pkg/runtime/alg.go @@ -0,0 +1,153 @@ +// Copyright 2014 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime + +import "unsafe" + +const ( + c0 = uintptr((8-uint64(ptrSize))/4*2860486313 + (uint64(ptrSize)-4)/4*33054211828000289) + c1 = uintptr((8-uint64(ptrSize))/4*3267000013 + (uint64(ptrSize)-4)/4*23344194077549503) +) + +const ( + alg_MEM = iota + alg_MEM0 + alg_MEM8 + alg_MEM16 + alg_MEM32 + alg_MEM64 + alg_MEM128 + alg_NOEQ + alg_NOEQ0 + alg_NOEQ8 + alg_NOEQ16 + alg_NOEQ32 + alg_NOEQ64 + alg_NOEQ128 + alg_STRING + alg_INTER + alg_NILINTER + alg_SLICE + alg_FLOAT32 + alg_FLOAT64 + alg_CPLX64 + alg_CPLX128 + alg_max +) + +var use_aeshash bool + +// in asm_*.s +func aeshash(p unsafe.Pointer, s uintptr, h uintptr) uintptr + +func memhash(p unsafe.Pointer, s uintptr, h uintptr) uintptr { + if use_aeshash { + return aeshash(p, s, h) + } + + h ^= c0 + for s > 0 { + h = (h ^ uintptr(*(*byte)(p))) * c1 + p = add(p, 1) + s-- + } + return h +} + +func strhash(a *string, s uintptr, h uintptr) uintptr { + return memhash((*stringStruct)(unsafe.Pointer(a)).str, uintptr(len(*a)), h) +} + +// NOTE: Because NaN != NaN, a map can contain any +// number of (mostly useless) entries keyed with NaNs. +// To avoid long hash chains, we assign a random number +// as the hash value for a NaN. + +func f32hash(a *float32, s uintptr, h uintptr) uintptr { + f := *a + switch { + case f == 0: + return c1 * (c0 ^ h) // +0, -0 + case f != f: + return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN + default: + return c1 * (c0 ^ h ^ uintptr(*(*uint32)(unsafe.Pointer(a)))) + } +} + +func f64hash(a *float64, s uintptr, h uintptr) uintptr { + f := *a + switch { + case f == 0: + return c1 * (c0 ^ h) // +0, -0 + case f != f: + return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN + case ptrSize == 4: + x := (*[2]uintptr)(unsafe.Pointer(a)) + return c1 * (c0 ^ h ^ (x[1] * c1) ^ x[0]) + default: + return c1 * (c0 ^ h ^ *(*uintptr)(unsafe.Pointer(a))) + } +} + +func c64hash(a *complex64, s uintptr, h uintptr) uintptr { + x := (*[2]float32)(unsafe.Pointer(a)) + return f32hash(&x[1], 4, f32hash(&x[0], 4, h)) +} + +func c128hash(a *complex128, s uintptr, h uintptr) uintptr { + x := (*[2]float64)(unsafe.Pointer(a)) + return f64hash(&x[1], 4, f64hash(&x[0], 4, h)) +} + +func nohash(a unsafe.Pointer, s uintptr, h uintptr) uintptr { + panic(errorString("hash of unhashable type")) +} + +func interhash(a *interface { + f() +}, s uintptr, h uintptr) uintptr { + return 0 +} + +func nilinterhash(a *interface{}, s uintptr, h uintptr) uintptr { + t := (*eface)(unsafe.Pointer(a))._type + if t == nil { + return h + } + fn := goalg(t.alg).hash + if **(**uintptr)(unsafe.Pointer(&fn)) == nohashcode { + // calling nohash will panic too, + // but we can print a better error. + panic(errorString("hash of unhashable type " + *t._string)) + } + if uintptr(t.size) <= ptrSize { + return c1 * fn(unsafe.Pointer(&(*eface)(unsafe.Pointer(a)).data), uintptr(t.size), h^c0) + } else { + return c1 * fn((*eface)(unsafe.Pointer(a)).data, uintptr(t.size), h^c0) + } +} + +// Testing adapters for hash quality tests (see hash_test.go) +func haveGoodHash() bool { + return use_aeshash +} + +func stringHash(s string, seed uintptr) uintptr { + return goalg(&algarray[alg_STRING]).hash(noescape(unsafe.Pointer(&s)), unsafe.Sizeof(s), seed) +} + +func bytesHash(b []byte, seed uintptr) uintptr { + // TODO: use sliceStruct + return goalg(&algarray[alg_MEM]).hash(*(*unsafe.Pointer)(unsafe.Pointer(&b)), uintptr(len(b)), seed) +} + +func int32Hash(i uint32, seed uintptr) uintptr { + return goalg(&algarray[alg_MEM32]).hash(noescape(unsafe.Pointer(&i)), 4, seed) +} + +func int64Hash(i uint64, seed uintptr) uintptr { + return goalg(&algarray[alg_MEM64]).hash(noescape(unsafe.Pointer(&i)), 8, seed) +}